Taylor Vortex Reactor | Continuous Flow Reactor for Advanced Chemical Materials

Advantages of Taylor Vortex Flow Reactor

1. Continuous Flow & High Yield Production

The Taylor Vortex Flow Reactor is equipped with feeding ports for continuous input of reactants and an outlet for reaction products. The continuous flow reaction set-up allows for improved heat transfer, mixing force, reproducibility, and scale-up of chemical reactions.

A study conducted at Korea Research Institute of Chemical Technology (KRICT) compared a Taylor Vortex Flow Reactor, vibration mill, and homogenizer for a zirconia bead emulsion polymerization. The results demonstrated that the Taylor Vortex Flow Reactor produced particles with highest yield, most uniform size and shape. More data can be found in our Taylor Vortex Flow Reactor brochure.

2. Combined Benefits of Batch Reactor and Plug Flow Reactor

The Taylor Vortex Continuous Flow Reactor provides the advantages of both tank-type reactors and plug flow reactors (PFRs), without the limitations of either type of reactor. Similar to tubular PFRs, the Taylor Flow Reactor produces remarkably high purity and uniform products with high repeatability. Both the homogenous micro-mixing zones and the high shear applied by the Taylor Vortex Flow makes this reactor ideal for manufacturing nano materials, as well. The continuous flow set-up also makes our Taylor Flow Reactor ideal for large-scale production for commercial products, similar to a tank-type reactor. Moreover, engineers and lab technicians can operate our reactors easily with minimal training.

1. High purity particle production
2. High repeatability
3. Suitable for nano materials manufacturing

Tank Reactor

1. Easy to operate, monitor, and control
2. Mixer function
3. Suitable for large-scale production

3. High Purity Materials Manufacturing

The Taylor Vortex Flow Reactor consistently produces higher purity particles than any other type of reactor on the market.

Compared to a batch tank reactor, which achieves a 51.5% purity with a single crystallization reaction and requires several batches to achieve a suitable purity, the Taylor Vortex Flow Reactor achieves a 98.2% purity in its first crystallization reaction.

4. Exothermic Reaction Control Feature

Temperature regulation is carried out by the circulating chiller/ heater of the Taylor Vortex Flow Reactor. The explosion control feature of the reactor improves safety by automatically adjusting the reactor temperature in the event of rapid heating. 

5. High Uniformity in Product Particle Size and Shape

The homogenous micro-mixing environment of the Taylor Flow Reactor enables consistent production of high density, uniformly shaped and sized particles.   

CSTR vs. LCTR: Microscopic Images of Product Particles

CSTR – Continuous Stirred Tank Reactor

LCTR – Continuous Taylor Flow Reactor

6. Reduced Cycle Time & Enhanced Production Efficiency

The vigorous homogenous micro-mixing zones, generated by the Taylor Vortex Flow, enhance mass transfer velocity by up to 4x and mixing force by up to 7x compared to a similarly sized batch reactor. Moreover, there are no “dead zones” within the reaction solution, which ensures that all reactants are being processed while in the reaction vessel.

As a result, our Taylor Vortex Flow Reactor can increase production capacity by a minimum of 2x to a maximum of 100x compared to similarly sized batch reactor or CSTR. For instance, the output of our 5L Taylor Continuous Flow Reactor is roughly equivalent to a 20L CSTR in a given reaction time.

Certifications

• CE certification
• ISO 9001 / ISO 14001

Patent Protected Taylor Vortex Reactor

United States

• Purification apparatus and method using continuous reactors (US 9,937,480B2)
• Apparatus and method for manufacturing particles (US 10,005,062B2)
• All-in-one continuous reactor and crystal separation apparatus for synthesis of positive electrode active materials for lithium secondary battery (US 10,010,851B2)
• Reaction device and reaction method for mixing (US 10,201,797B2)

Europe

• Apparatus for manufacturing particles and method utilizing apparatus for manufacturing particles (EP 3012019B1)
• All in one continuous reactor and crystal separation apparatus for manufacturing positive electrode active material for lithium secondary battery (EP 2735366B1)
• Purification apparatus and method using continuous reactors (EP 2893964B1)

Japan

• All-in-one type continuous reactor and crystal separation apparatus for synthesis of positive electrode active material for lithium secondary battery (JP 5714708)
• Reaction device and respective manufacturing method for mixing (JP 6257636)
• Refining device and method for continuous reactor (JP 6352919)
• Manufacturing device and method for quantum dots (JP 6568265)

South Korea

• Reaction device and manufacturing method for mixing (10-1092337)
• Polarizing film to waste recovery of potassium iodide (10-2241620)
• Special cylinder for reactor (10-1239163)
• Gas-liquid reactor and reaction method for lithium secondary cathode materials (10-1361118)
• High-pressure reaction apparatus (10-1364691)
• Tryptophan purification devices and methods (10-1372811)
• Solid-liquid mixed reaction apparatus (10-1399057)
• An apparatus and method for synthesis of particles (10-1464345)
• An apparatus and method for synthesis of core-shell particles (10-1424610)
• Ultra-high purity purification device including a continuous reactor (10-1427324)
• Surface treatment method using Taylor-Couette Flow Reactor (10-1727939)
• Methods and devices for manufacturing non-oxidizing graphene using electrochemical pretreatment and shear flow exfoliation (10-1785374)
• Graphene metal nanoparticle complex (10-1866190)
• Manufacturing system and method using Couette-Taylor reactor for graphene oxide synthesis (10-1573384)
• Eco-friendly graphene oxide synthesis system using Taylor-Couette reactor (10-1573358)

Certificates

Business Case: Taylor-Couette Reactor for Production of Graphene Oxide and Graphene Materials

Taylor Vortex Reactor for Graphene and Graphene Oxide Business Case

A large-scale 2D graphene producer based in the Midwest US chose our 10L Taylor Vortex Reactor to maintain their market advantage and innovative leadership in global graphene production. The client produces single- and few-layer graphene and graphene oxide for applications in electric vehicle (EV) battery, nanomaterials for thermoplastics, conductive films, energy storage, and more.

Already holding hundreds of patents in graphene production technology, the client invested in our continuous flow reactor to further enhance the quality and capacity of their graphene R&D laboratories.

Graphene: Applications and Conventional Manufacturing Processes

Graphene is a 2D carbon material with a hexagonal molecular structure. It is one of the strongest and thinnest materials in the world, and it won the 2010 Nobel Prize in Physics for its extraordinary properties. Graphene’s excellent electric and thermal conductivity makes it the basis of many next-generation solutions for energy storage, electric vehicles (EVs), solar cells, and more.

While well-known methods of graphene production exist, including Hummer’s method, sonication exfoliation, and homogenization exfoliation, graphene has traditionally been expensive and difficult to produce. Each of the above methods have significant limitations, such as environmental concerns, low yields, complex multi-step processes, and the production of small, uneven flakes. These limitations prevent industrial-scale production of graphene, which should be high quality, low cost, high yield, and environmentally friendly.

Taylor Vortex Reactor: New Method for Graphene Oxide Synthesis

Recently, the literature on graphene oxide synthesis via the Taylor Vortex Reactor has been growing. Also referred to as Taylor-Couette Flow Reactor, Couette-Taylor Flow Reactor, Stress Shearing Reactor, the reactor’s production of purer, more uniform, more efficient, and higher yields of graphene oxide and graphene flakes has been replicated in several studies across the world.

Below, we summarize findings from several peer-reviewed studies that highlight the advantages of using a Continuous Vortex Flow Reactor for graphene oxide synthesis.

In short, the advantages for our graphene-producing clients include:

• Shortened reaction time with continuous synthesis
• High yield production rates
• High quality products with low defect rates
• Structurally uniform products with larger flake sizes
• Easy operation of reactor that gives control over product geometry
• Reduced water and acid waste for green synthesis

Advantages of Taylor Flow Reactor for Graphene Oxide Synthesis

1. Shortened Reaction Time with Continuous Synthesis

In 2019, the Taylor-Couette Flow Reactor “revolutionized the synthesis of graphite oxide” by shortening the time of oxidation from 4 hours with the Hummer’s method to 30 minutes (AlAmer et al., 2019). Despite the drastically shortened reaction time, the resulting graphite oxide sheets were uniformly structured with low defect rates and high yields.

Park et al. (2017) also compared the Hummer’s method and the Couette-Taylor Reactor for graphene oxide synthesis. They found that a 60-minute oxidation reaction in the Couette-Taylor Reactor resulted in a 98% yield of uniform, large-area flakes of few-layer graphene oxide. In contrast, the Hummer’s method produced a 34% yield within the same reaction time.

2. High Yield, High Quality, Uniform Graphene and Graphene Oxide

Few-layer graphene via non-oxidative exfoliation was also produced by Tran et al. (2016) with LPR Global’s Taylor Vortex Flow Reactor. The researchers concluded that our reactor demonstrates high potential to produce high quality graphene on an industrial scale. After measuring the AFM height of more than 250 flakes, the study found that 90% of the flakes were composed of fewer than 5 layers. Raman spectroscopy also indicated low defect rates, with a Raman D/G band intensity ratio (I_D/I_G) of 0.14. An XPS also showed no evidence of oxidation, which suggests that the Taylor Vortex Reactor produced high quality graphene flakes.

Moreover, Park et al. (2017) also found that the lateral size of the graphene oxide sheets was easily manipulated by simply adjusting the rotational speed of the Taylor Vortex Flow Reactor and the reaction time. This finding is a significant improvement from sonication and homogenization methods, both of which tear graphene flakes into small, uneven pieces.

Graphite oxide synthesis via the Taylor-Couette Reactor was also found to produce assessed uniformly structured graphite oxide sheets with low defect rates and high yields by AlAmer et al. (2019). Due to the wall shear exfoliation induced by the rotating inner cylinder, the number of graphite layers decreased from ~85 layers (natural graphite) to ~8 layers. Raman spectroscopy was also used to confirm high homogeneity in the geometry of the graphite oxide produced by the vortex flow regime.

Expandable Graphite and Few-Layer Graphene for Graphene Fiber

In a separate study, AlAmer et al. (2020) compared the Taylor-Couette Reactor to conventional batch processes for the exfoliation of natural graphite. Graphite exfoliation produces expandable graphite and few-layer graphene, which can be spun into ultralight graphene fiber and have high commercial applicability. The high shear rates achieved during the vortex flow regime resulted in structurally homogenous few-layer graphene sheets with large lateral dimensions of over 10 µm. This was an important finding, as flake size is a significant determinant of macroscopic fiber properties, in that larger flake sizes led to stronger fibers.

Notably, only 1-3 hours of shearing time were required to achieve expandable graphite and few-layer graphene with almost no defects. The resulting graphene fiber (bulk density 0.35g/cm³) displayed a mechanical strength of 0.5 GPa without any modification or heat treatment. The figure below shows that graphene fibers spun with the Taylor-Couette Reactor’s expandable graphite display significantly better mechanical properties than fibers using commercially available expandable graphite.

3. Green Synthesis with Reduced Acid and Water Waste

Unlike the Hummer’s method, the Taylor Vortex Flow Reactor successfully produced high yields of graphene oxide at low viscosities of under 200 cP (Park et al., 2017). The low-viscosity mixture allowed for an initial separation H₂SO₄ from the graphene oxide slurry with a simple filtration system. Subsequently, the purification of the graphene oxide product used 75% less water compared to the Hummers’ method. The finding of this study overcomes one of the greatest limitations of the Hummer’s method: its inability to produce high yields of graphene oxide from low-viscosity mixtures, which then requires great amounts of water for acid purification.

Moreover, Park et al. (2017) found that graphene oxide synthesis with once- and twice-recycled filtered H₂SO₄ for produced comparable quality and yield. Recovery rates for graphene oxide produced with fresh, once-recycled, and twice-recycled H2SO4 were approximately 98.5%, 97.1%, and 97.9%, respectively.

Customizable Reactor for Pilot-Scale Production

The 10L Taylor Vortex Reactor used by this client is ideal for pilot-scale production. The standard model has a maximum agitation speed of 1500 RPM and maximum reaction temperature of 90°C. Having said that, this Continuous Flow Reactor can also be customized for higher agitation speeds and reaction temperatures.

The user-friendly PLC interface also allows our client to save their reaction data, thereby facilitating their reaction optimization process.

For questions on how LPR Global’s Taylor Flow Reactor can enhance your advanced materials manufacturing, please reach out to [email protected].

References

AlAmer, M., Lim, A. R., & Joo, Y. L. (2018). Continuous synthesis of structurally uniform graphene oxide materials in a model Taylor–Couette flow reactor. Industrial & Engineering Chemistry Research, 58(3), 1167-1176.

AlAmer, M., Zamani, S., Fok, K., Satish, A., Lim, A. R., & Joo, Y. L. (2020). Facile Production of Graphenic Microsheets and Their Assembly via Water-Based, Surfactant-Aided Mechanical Deformations. ACS applied materials & interfaces, 12(7), 8944-8951.

Park, W. K., Yoon, Y., Kim, S., Choi, S. Y., Yoo, S., Do, Y., Jung, S., Yoon, D. H., Park, H. & Yang, W. S. (2017). Toward green synthesis of graphene oxide using recycled sulfuric acid via couette–taylor flow. ACS omega, 2(1), 186-192.

Park, W. K., Yoon, Y., Song, Y. H., Choi, S. Y., Kim, S., Do, Y., Lee, J., Park, H., Yoon, D. H., & Yang, W. S. (2017). High-efficiency exfoliation of large-area mono-layer graphene oxide with controlled dimension. Scientific reports, 7(1), 1-9.

Tran, T. S., Park, S. J., Yoo, S. S., Lee, T. R., & Kim, T. (2016). High shear-induced exfoliation of graphite into high quality graphene by Taylor–Couette flow. RSC advances, 6(15), 12003-12008.

Taylor Vortex Reactor for Graphene and Graphene Oxide Business Case

Business Case: Taylor Crystallizer for Next-Generation EV Battery Materials

Taylor Crystallizer for EV Battery Materials Business Case

LG Chem, a global leader in chemical manufacturing and R&D, as been using our pilot-scale 50L Taylor Crystallizer for advanced chemical research since 2012. LG Chem and its battery-focused subsidiary, LG Energy Solutions, are one of the most active companies in EV battery manufacturing with partnerships with General Motors (LG Energy Solutions) and Stellantis (LGES).

Our Taylor-Couette Reactor is being explored as a key technology to build entire supply chains for advanced battery materials in the U.S.

Our Taylor-Couette Crystallizer is also the chosen technology used by researchers at Argonne National Laboratory (ANL), the MEET Institute at the University of Münster, and the ZSW Institute in Germany.

Our proprietary LCTR Taylor crystallizer is the cornerstone of BAT167, a project commissioned by the U.S. Department of Energy’s Vehicle Technology Office for the development of efficient, affordable EV battery technology. Argonne National Laboratory has been using our Taylor-Couette Crystallizers, AKA Taylor Vortex Reactor since 2015 to manufacture advanced lithium ion battery materials. As stated in a recent review by the DOE, the Taylor Vortex Reactor is proving critical “to synthesize materials at a scale that bridges the needs of academia and industry-scale research and development (R&D).” (2021 VTO Annual Merit Review)

Argonne National Laboratory’s public research compares the Taylor Vortex Reactor with batch tank reactors, continuous stirred tank reactors, and other conventional technologies, while providing advanced material samples to partnering research teams.

The Taylor-Couette Crystallizer is contributing to the mission of replacing fuel-based vehicles with EV battery technology by 2050 via both commercial and R&D streams of production. This article will review the Taylor Vortex Reactor’s application and performance for the following competing technologies:

1. NMC Battery Materials
   1. Ni-Rich Hydroxide via Crystal Agglomeration
   2. High-Capacity Mn-Rich Cathode Materials
   3. Core Shell NMC Battery Material
2. Cobalt-free Lithium Battery Material
   1. Pilot-Scale Production of Spherical Co-Free Cathode Materials
   2. Co-free and Mn-free Cathodes for LIBs
3. NCA Hydroxide for Cathode Material
4. All Solid State NMC Battery Materials
   1. Ga-Doped LLZO Material
   2. Composite NCM-LZAOH Solid State Battery
5. Na-ion Battery Nanomaterials

Jump to References

Research for each advanced battery technology is ongoing, and several technologies may have a role in our future battery landscape based on their unique properties.

Advanced Battery Materials Manufacturing

The U.S.’s battery research field is expanding and growing in diversity with key technologies including lithium-ion battery, NMC battery, Co-free, Na-ion, solid state, and core-shell battery technology. For many technologies, common obstacles for battery R&D include high toxicity, high cost, and ethical sourcing concerns.

As a result, commercial and academic R&D industries are on a mission to develop battery technology that is high-performing, safer, more affordable, and more sustainable for mass production.

Next-Generation Battery Particles are often manufactured via co-precipitation or chemical crystallization. Characteristics indicating high-quality battery particles include:

• Spherical and uniform morphology, which lends the particles the desirable qualities of high tap density and structural integrity.
• Narrow particle size distribution is also an indication of that electrochemical performance and structural integrity of the battery will be consistent and uniform across the battery cell.
• Particle size to increase relative surface area. This is critical for powerful electrochemical performance, as the chemical reaction that produces energy occurs at the surface of the particles.

The precursor characteristics are heavily dependent on the crystal agglomeration mechanism, which depends on synthesis conditions, including reactor type and layout (Schmuch et al., 2020).

Taylor Vortex Reactor for Advanced Battery Materials

The Taylor Vortex Reactor (commonly referred to as Taylor Crystallizer, Taylor Flow Reactor, or Taylor-Couette Reactor) is a continuous flow reactor. It utilizes Taylor-Couette flow dynamics, which generate uniform “micro-mixing zones” with high shear force to create superior reaction kinetics while eliminating stagnant zones.

Read more on Taylor Crystallizer mechanism

The result is higher mass transfer, heat transfer, and fluid shear force compared to batch or continuous stirred tanks of comparable volumes. The Taylor crystallizer improves purity, morphology, particle size distribution, and crystallinity of particle products. Due to its continuous design and micro-mixing zones, the Taylor Crystallizer also displayed improved scalability from lab-bench to pilot to mass production scale projects.

With options of pH control, temperature control, and easily adjustable mean residence time and hydrodynamic conditions via rotational speed, the Taylor Vortex Reactor creates further possibilities for R&D and mass production of advanced battery technology.

1. Taylor Crystallizer for NMC Battery Material for High-Energy LIBs

NMC Battery materials (LiNi_xMn_yCo_zO₂, where x + y + z = 1) are one of the largest categories of new lithium-ion battery materials.

In 2020, MEET Institute’s Dr. Richard Schmuch and colleagues published a valuable overview of the Taylor Vortex Reactor for NCM811 cathode materials for EV batteries. In summary, they find that the TVR produces cathode materials with high densities, large particle size, bimodal size distribution, and spherical morphology.

Read the MEET Institute’s Review here:

Excerpt Nickel-Rich Layered Cathode Materials for High-Energy Lithium Ion Batteries via a Couette-Taylor Flow Reactor

R. Schmuch, V. Siozios, M. Winter and T. Placke (University of Münster, MEET Battery Research Center), 2020

1.1 Ni-Rich Hydroxide via Crystal Agglomeration

The production of Ni-rich NMC battery materials by D. K. Thai, Q.-P. Mayra and W.-S. Kim (2014) focuses on crystal agglomeration. It compares the performance of the Taylor Vortex Reactor with that of a continuous mixed-suspension mixed-product removal (MSMPR) crystallizer.

Crystal Agglomeration of NMC Hydroxide

Crystal agglomeration involves two consecutive processes:

1. Crystal aggregation

Aggregates form via the collision and physical binding of individual crystals caused by the velocity of the fluid motion. Simultaneously, the velocity of the fluid motion also creates a hydrodynamic fluid shear force that re-disperses the crystal aggregates.

2. Molecular Growth

The aggregates must bind strongly enough to resist the hydrodynamic fluid shear force. This process is controlled by mass transfer velocity, whose effect on molecular growth is not linear.

At the time of this study, it was already established that NMC batteries with a Ni-rich hydroxide precursor have high reversible electric capacity (>200 mAh/g). Specifically, spherical precursor particles with a narrow PSD have high packing density and surface area for efficient charge transfer. Precursor materials with these characteristics are demonstrated to have high electrochemical performance.

Enabled by the Taylor Reactor’s easy operability, Thai et al. (2015) manipulated rotational speed, residence time, and pH to examine NMC hydroxide formation under various conditions. Additionally, the researchers compared crystal agglomeration via the Taylor Crystallizer’s various flow patterns (Taylor vortex flow, wavy vortex flow, modulated wavy flow, etc.) to agglomeration via the turbulent eddy flow of the MSMPR crystallizer.

NMC Battery Set-Up With Taylor Crystallizer

Thai et al.’s Taylor Crystallizer had three ports along axial direction of the reactor. These ports allowed for sampling at different points of the crystallization process.

Hydrodynamic Fluid Motion: The hydrodynamic conditions within the Taylor Crystallizer were controlled by adjusting the rotation speed of the inner cylinder from 300 rpm to 1500 rpm. The rotation speed is easily adjusted with a simple dial or via our touchscreen PLC system, which also displays other reaction parameters.

Mean Residence Time: The mean residence times of 5 min to 60 min were controlled by varying the flow rates of the feed solutions.

pH: A pH sensor was used to monitor the pH of the reaction, which was maintained between 10.0 and 13.0 by adjusting the flow rate of the NaOH solution. This adjustment can be done automatically by connecting the pH sensor to our solution pump.

NMC Battery Materials Produced Taylor Crystallizer

The Taylor Crystallizer produced NMC hydroxide particles with varying PSDs, depending on rotational speed and mean residence time. Thai et al. (2015) found that the most uniform and spherical particles were produced at a rotational speed of 1500 rpm and a mean residence time of 30 min.

Particle morphology of Ni-rich hydroxide also varied according to reaction parameters, as summarized below.

Rotation Speed: 700 rpm, Mean Residence Time: 15 min

• NMC Hydroxide Particles at First Sample Port: 15 µm with a PSD of 0.67 CV
• NMC Hydroxide Particles at Outlet: 6 µm with a PSD of 0.51 CV

Rotation Speed: 1500 rpm, Mean Residence Time: 30 min

• NMC Hydroxide Particles t First Sample Port: 4.5 µm
• NMC Hydroxide Particles at Outlet: 3.6 µm

Generally, particle size distribution and particle shape are key determinants for the tap density of NMC battery precursors. Prolonged residence time extended the exposure of the Ni-rich hydroxide particles to the Taylor Crystallizer’s fluid shear forces. As a result, particles became more spherical which, in turn, increased tap density.

The particles produced at 1500 rpm with a mean residence time of 60 min had a tap density of 2.13 g/cm³, the highest of any previously reported values.

Thai et al. (2015) also demonstrated the importance of pH in the formation of Ni-rich hydroxide particles. By controlling the pH of the reaction by adjusting NaOH flow rate, varying pH levels were examined for NMC hydroxide particle formation. In the present study, they found that optimal Ni-rich hydroxide formation occurs at a pH of 12.0.

Taylor Crystallizer vs. MSMPR Crystallizer for NMC Battery Materials

Thai et al. (2015) compared the performance of a Taylor Crystallizer (AKA Taylor Vortex Reactor) with that of a Rushton-type MSMPR crystallizer. Reaction parameters were kept at the following constants:

• Rotation / agitation speed: 1200 rpm
• pH: 12.0
• Ammonia concentration: 15.0 mol/L
• Mean residence time varied as follows:
  • Taylor Crystallizer: 30 to 60 min
  • MSMPR Crystallizer: 270 to 720 min

NMC hydroxide particles produced the Taylor Crystallizer for 30 min were 3.2 µm in size. In comparison, the MSMPR Crystallizer only produced particles of 5.2 µm in 12 h.

As mentioned above, hydrodynamic fluid shear is a critical force in producing spherical and uniformly sized particles. When comparing viscous energy dissipation, the Taylor Crystallizer displayed equivalent fluid shear at 300 rpm as the MRMPR’s random turbulent flow at >800 rpm. This helps explain why the Taylor Crystallizer produces the desired particles in a fraction of the time required by the MSMPR crystallizer.

While the MSMPR produced particles with higher tap density after 12 h, the drastically shorter residence time of the Taylor Crystallizer suggests that it is more productive and practical for Ni-rich hydroxide production.

1.2 High-Capacity Mn-Rich Cathode Materials

LiCoO₂ is an important commercial material due to its high electrochemical performance. However, both lithium and cobalt face cost, toxicity, safety, ethical sourcing concerns. To explore cheaper and safer alternatives for high-capacity cathode materials, M. Choi et al. (2014) synthesized NMC rich in manganese.

NMC battery materials co-precipitation in a Taylor crystallizer.

• Materials sourcing: Daejung Co., Aldrich Korea, J.T. Baker
• Mean residence time: 50 min
• Rotation speed: 1500 rpm

Narrow PSD was observed with total residence times of from 150 min to 750 min residence times. With increasing reaction time, increasing mean particle size and narrowing PSD were observed.

• Spherical morphology, 7-8 µm in diameter (FE-SEM)
• Secondary particles formed by agglomeration of smaller particles <200 nm in diameter

Spherical cathode particles with rough surfaces were synthesized with a shorter reaction time in the Taylor-Couette reactor. The NMC cathode material is expected to demonstrate good high-rate electrochemical performance due to good absorption of the electrolyte.

• XRD Patterns: well-defined hexagonal structure, superlattice ordering of Li and Mn in transition-metal layers, uncontaminated lithium layer
• ICP Analysis: near-theoretical chemical compositions of NMC hydroxide precursor and Li-NMC cathode material

Coin-type cells were prepared with the Mn-rich NMC battery materials and tested for electrochemical performance. Discharge capacities:

• First charging capacity at 110 mAh/g: 4.45 V
  • Corresponds with theoretical capacities associated with oxidation of Ni and Co ions.

1.3 Core Shell NMC Battery Material

The Taylor Crystallizer has also been used to successfully produce uniform and spherical core-shell particles for high-performing NMC battery materials by Kim & Kim (2018). Core particles and shell particles were separately synthesized in the Couette-Taylor Crystallizer. Core and shell particles were simultaneously fed into the Taylor Reactor and made to adhere via collision and agglomeration within the reactor.

Core-shell NMC production with the Taylor Crystallizer was compared with an MSMPR Crystallizer.

Experimental Set-Up of Couette-Taylor Core Shells

The Ni-rich NMC core particles were prepared via continuous precipitation in a Taylor Vortex Reactor with a Ni:Mn:Co ratio of 90:5:5.

• Temperature was maintained at 50°C with regulating jackets
• Mean residence time of 60 min
• Rotational speed of 1500 RPM
• pH was maintained at 12.5 by the automatic adjustments made to the flow rate of the NaOH solution upon feedback from the crystallizer’s pH sensor.

The Ni-Mn “half-half” shell particles were also prepared in the Couette-Taylor Crystallizer, at a Ni:Mn:Co ratio of 47.5:47.5:5.

These compositions maximized the advantages of Ni, Mn, Co while minimizing the high cost associated with cobalt. Based on prior research, high nickel and cobalt content increases electrochemical performance, while high manganese increases stability. Therefore, the Ni-rich NMC core was structured for high electrochemical performance, while the half-half Ni-Mn shells was structured for high structural and thermal stability.

Core-Shell Particles

The purpose of the shell layer is to protect core particles from the toxic environment created within a battery cell. Thickness and uniformity of the shell layer are critical determinants of the properties of the core-shell particle. If the shell layer is too thin, it is unable to stabilize the core particle. However, if the shell layer is too thick, it will lower the electrochemical capacity of the core. Moreover, highly spherical and uniform core particles are crucial in increase packing density, which increases overall electrical capacity of the battery cathode.

These critical characteristics are determined by the precipitation process of the core and shell particles. Therefore, the quality and productivity of the crystallizer are of utmost importance in producing high-quality, scalable core-shell NMC battery materials.

Core-Shell Synthesis via Collision and Agglomeration

Once the core and shell particles were precipitated, they were simultaneously fed into the Couette-Taylor Crystallizer for collision and agglomeration processes.

• Mean residence time varied from 20 to 120 min by adjusting the flow rates of the feed solutions
• Rotational speed varied from 300 to 1500 RPM to adjust the hydrodynamic conditions within the reactor
• pH varied from 9.5 to 11 by adjusting the flow rate of the NaOH reactant solution.

The MSMRP Crystallizer was a standard Rushton-type mixing tank with four baffles, a three-blade impeller, and a heating jacket on the wall of the reactor.

Results of Core-Shell NMC Battery Synthesis in Couette-Taylor Crystallizer

• Morphology: spherical, uniform
• Mean particle size: 12.5 µm with 0.15 CV
• Tap density: 2.26 g/mL *The best value represented in literature at the time
• Energy dispersive spectroscopy (EDS) microscopic cross-section: 1-2 µm uniform shell layer
  • Experimental confirmation of theoretical compositions: Ni-Mn half-half hydroxide shells and Ni-rich NMC core particles.

Sample Outlet Ports & Varying Hydrodynamic Conditions

Moreover, the researchers’ Taylor Vortex Reactor was configured with multiple outlet ports along the length of the reactor. This allowed Kim & Kim (2018) to sample materials throughout the agglomeration process.

They found that the shell thickness increased monotonically along the length of the Couette-Taylor Crystallizer. Shell thickness also increased when the rotational speed was reduced and when the shell solution concentration increased. In other words, shell layer formation depended heavily on the adjustable operating parameters of the Couette-Taylor Crystallizer, the reactant concentration, and the residence time.

By adjusting the rotational speed of the inner cylinder, Kim & Kim (2018) generated different hydrodynamic conditions with the Taylor Crystallizer. This allowed them to observe the effect of different fluid motions on shell layer formation. Based on their quantitative observations, they concluded that the collision of primary-core particles is directly dictated by the fluid motion dominating the reaction.

NMC Core-Shell Synthesis: Taylor Crystallizer vs. MSMPR Crystallizer

Kim & Kim (2018) compared core shell synthesis in a Taylor Crystallizer to an MSMPR Crystallizer. The Taylor Crystallizer generated variations of the Taylor flow as the dominant hydrodynamic conditions. In contrast, the MSMPR generated a random turbulent eddy with a 6-blade impeller.

A mean residence time of over 8 hours was required to form the desired core-shell particles in the MSMPR. When mean residence time was increased to 12 hours, both the thickness of the shell layer and the tap density of the core-shell particles.

Taylor Crystallizer

• Mean Residence Time: 1 h
  • Shell layer thickness: 1.4 µm
  • Tap density: roughly 2.04 g/cm³

• Mean Residence Time: 1.5 h
  • Shell layer thickness: 2.1 µm
  • Tap density: roughly 2.06 g/cm³

MSMPR Crystallizer

• Mean Residence Time: 8 h
  • Shell layer thickness: 1.3 µm
  • Tap density: 2.0 g/cm³

• Mean Residence Time: 12 h
  • Shell layer thickness 1.6 µm
  • Tap density: 2.15 g/cm³

While the core-shell characteristics were desirable, synthesis in a MSMRP Crystallizer required significantly longer reaction time than in a Couette-Taylor Crystallizer. Therefore, the researchers concluded that the Taylor-Couette Crystallizer is 10 times more efficient in producing NMC core-shell particles than a conventional MSMPR Crystallizer due to the Taylor vortex fluid motion.

2. Cobalt-Free Cathode Material

2.1 Pilot-Scale Production of Spherical Cobalt-Free Cathode Powder

In partnership with the German Federal Government, ZSW has been developing next-generation lithium-ion battery materials with our Taylor Vortex Reactor. Specifically, they are developing cobalt-free cathode materials to increase specific energy, or energy density, while cutting costs of lithium batteries.

With our 1L Taylor Vortex Reactor, ZSW synthesizes spherical cathode powders in the scale of 10 kg to 30 kg for electrode coating and cell assembly.

Excerpt of the ZSW Annual Battery Report 2020

2.2 Cobalt-Free and Manganese-Free Cathodes for Lithium-Ion Battery

In a study by S. Aryal et al. (2021), the Materials Engineering Research Facility (MERF) at Argonne National Laboratory utilized our 1L Taylor Vortex Reactor (TVR) to study the effect of Mn and Co on Ni-rich layered cathode materials. Our Taylor Vortex Reactor was specifically selected for its scalability from R&D to large-scale production. In contrast, a small batch reactor is difficult to scale up for large-scale production.

Aryal et al. (2021) compared the performance of NMC, Co-free, and Mn-free cathode materials, which were all co-precipitated in the Taylor Vortex Reactor:

• Ni_0.9Mn_0.1(OH)₂
• Ni_0.9Co_0.1(OH)₂
• Ni(OH)₂

MERF’s study was the first to published experiment in which the three compositions were synthesized via the same method in a Taylor Vortex Reactor and studied under identical conditions.

Taylor Crystallizer Set-Up

• Metal sulfate solutions, NH₄OH (ammonia) and NaOH (sodium hydroxide) were continuously fed into the reactor via 3 separate pumps
• The pH of the solution was maintained between 11 and 12
  • pH sensor was connected to the NaOH pump and automatically adjusted the flow rate to maintain desired pH.
• Temperature was fixed at 50°C, and was monitored by a temperature sensor
• Rotational speed was maintained at roughly 800 RPM

Mn-free and Co-free Battery Materials with Taylor Vortex Reactor

The Ni-rich battery materials synthesized in the Taylor Vortex Reactor were similar in size and spherical surface morphology. Primary particles of 200 nm – 300 nm aggregated to form secondary particles with an average size of 10-15 µm.

Tap Density:

• LNO: 1.99 g/cc
• LNMO: 2.14 g/cc
• LNCO 1.82 g/cc

The high tap density of LNMO is due to individually denser particles, as well as a narrower particle size distribution, which allows for denser packing.

In conclusion, MERF researchers found that Co-free LNMO cathode material demonstrates highly stable cyclic performance and is a noteworthy contender for sustainable next-generation Li-ion battery material.

Better understanding of the effect of Co and Mn is expected to inform future NMC battery compositions for superior performance, sustainability, and safety.

3. Uniform and Stable NCA Hydroxide for Cathode Material

The Taylor Vortex Reactor’s uniform and constant mixing forces were used by M. Seenivasan et al. (2020) to prepare spherical and uniform Ni_0.80Co_0.15Al_0.05(OH)₂ particles with the following characteristics:

• Elemental mapping (EDX): Ni, Co, Al uniformly present in near-stoichiometric ratios of 78.5%, 16.1%, and 5.4%, respectively.
• Crystal structure (XRD): Diffraction peaks indexed to hexagonal phase of β-Ni(OH)₂. Lack of peaks for impurity phases indicates a pure phase product.
  • Rietveld refinement analysis further shows suggests that Taylor-made NCA hydroxide had highly ordered crystalline layers.
  • R-factor intensity ratios >1.2 indicate low cation mixing, small irreversible cation loss, and therefore, good electrochemical performance.
  • Intensity ratios of Taylor-made NCA hydroxide materials ranged from 1.810 to 1.639, indicating greater than recommended value and previously reported values NCA cation-mixing.

• Morphology and microstructure (SEM, HR-TEM): spherical particles with average sizes of 5-6 µm. Polyhedral primary particles of sizes varying from 200 to 1 µm.
  • As smaller primary particle sizes indicate shorter diffusion pathways for Li⁺ migration, they are a critical consideration for de/intercalation.

• Chemical composition (ICP-OES): experimental confirmation of stoichiometric compositions
• Electrochemical performance via preparation of CR2032 coin-type half-cells: rate capabilities in discharge range of 0.2-10C at 25°C with fixed charge rate at 0.2C
  • NCA-750 exhibited superior reversible capacity of 138.1 mAh/g at 10C. NCA-775 and NCA-800 exhibited capacities of 134.4 and 116.6 mAh/g, respectively.
  • All the Taylor-made samples demonstrated higher reversible capacities than cathodes prepared with commercially available NCA.
• Cycle Life over 100 cycles:
  • NCA-750 had initial capacity of 162.7 mAh/g and a 100^th capacity of 145.1 mAh/g, for a retention of 87.4%. In comparison, the commercial NCA sample had a capacity retention of only 70.0%.

Seenivasan et al. (2020) concluded, “a Couette-Taylor flow vortex is highly efficient medium for the preparation of Ni-rich hydroxides in a homogenous phase and with spherically intact secondary particles.”

4. Solid State Lithium Battery

4.1 Ga-Doped LLZO Material

Researchers from KITECH (2017) compared the synthesis of Ga-doped LLZO for solid state batteries in a Taylor-Couette Reactor vs. a batch tank reactor.

While LLZO (Li₇La₃Zr₂O₁₂) is a metal oxide with excellent ionic conductivity and good electrochemical windows, it is difficult to prepare cubic-phase pellets with fine sintering properties. LLZO is particularly sensitive to process conditions, yet co-precipitation was thought to be a promising method for mass production. At the time of the publication, the highest ionic conductivity of LLZO prepared via conventional means is approximately 3-8 × 10^-4 S/cm.

In this publication, Yang et al. (2017) experimented with a new method of LLZO co-precipitation via the Taylor Flow Reactor to examine how the unique Taylor vortex fluid motion affects LLZO properties.

They report that the toroidal vortex fluid motions created highly efficient radial mixing conditions, which led to reduced reaction time and increased yield. Simultaneously, the Taylor Vortex Reactor produced Ga-doped LLZO materials with lower crystallite size, and higher density and ionic conductivity, when compared to a batch reactor.

The toroidal vortex motion in the Taylor Crystallizer increased lattice parameter, which proportionately increased ionic conductivity while decreasing crystallite size. As seen in the values above, the total conductivity of the oxide-based LLZO pellet prepared in the Taylor Crystallizer approximates the high value of sulfide-based pellets.

In conclusion, Yang et al. (2017) demonstrated that the Taylor-Couette Crystallizer makes it possible to efficiently produce high-performing, spherical nanomaterials for solid state batteries.

4.2 Composite NCM-LZAOH Solid-State Battery

In 2020, Heo et al. compared NCM80 and composite NCM80-LZAOH cathode materials for all-solid-state battery performance. Both the NCM80 and the composite NCM80-LZAOH material were synthesized in our 1L Taylor Vortex Reactor via co-precipitation.

The reactor was configured with a pH sensor that connects to the NaOH pump. The flow rate of the NaOH pump automatically adjusted throughout the reaction to maintain a reaction pH of 11 for 4 hours.

Results of NCM vs. Composite NCM-LZAOH Synthesis

FE-SEM images of both NCM80 and composite NCM-LZAOH materials display spherical particles with similar particle sizes of <5 µm. FE-TEM images further show that the primary particles were 100 to 200 nm in size.

Additionally, TEM images show that the composite NCM-LZAOH material had a uniform coating layer roughly 10 nm thick, composed of nanomaterials 1-2 nm big, which was not present on NCM80 particles. EDS mapping images also demonstrated that the composite elements were uniformly distributed on the material surface, which indicates uniform coating of LLZAO material.

Furthermore, ICP analysis of both NCM80 and composite NCM-LZAOH reveal that the experimental atomic contents closely approximate the theoretical values. The ICP results indicates that the elements were uniformly distributed during co-precipitation in the Taylor Crystallizer.

Overall, the experiment found that the composite NCM-LZAOH cathode material presented higher initial discharge, initial coulombic efficiency, and discharge retention after 50 cycles when compared to the NCM80 material.

The study by Heo et al. (2020) is valuable in demonstrating the use of the Taylor-Couette Crystallizer to synthesize various particles with spherical morphology, uniform composition, and high electrochemical performance for next-generation solid state batteries.

5. Na-ion Cathode Material via Taylor-Couette Reactor

Finally, the Taylor-Couette Crystallizer’s ease of operation for manufacturing of new battery technology is well demonstrated by the 2017 study by Jo et al.

Prompted by concerns about high cost, low lithium availability and poor safety of Li-ion batteries, the researchers manufactured various Na-ion battery cathode materials. Layered Na-ion materials show improved conductivity and capacity with carbon coating and transition metal substitution.

By adjusting the reaction temperature of our Taylor-Couette Reactor, Jo et al. (2017) manufactured Na­_xMn[Fe(CN)₆]•zH₂O with varying crystal structures. They then evaluated the effects of varying Na and interstitial water content on the crystal structure and electrochemical properties of the Na-ion battery material.

Taylor Crystallizer Temperature Control Function

Na-ion battery materials were produced at a reaction temperature of 25°C and 60°C.

Our Taylor-Couette Crystallizer allows for adjustable reaction temperatures of up to 90°C. Our high-temperature model extends this control to up to 300°C.

The temperature of the reaction solution is control with our temperature regulating jackets that wrap around the entire exterior of the reaction tank. The high surface area of the cylindrical design of our Taylor Vortex Reactor allows for greater control and adjustability of the reaction temperature.

Experimental Results of Na-ion Battery Materials Manufactured in Taylor-Couette Reactor

The temperature control function of the Taylor Vortex Reactor allowed the Jo et al. (2017) to examine the different crystal structures produced at varying temperatures and drying processes. In conclusion, they found that agglomeration of Na-ion cathode material was preferred at high reaction temperatures.

Cathodes were prepared with a coating of the Na-ion material, then tested for electrochemical performance and stability. Overall, the cubic crystals synthesized at 25°C and air-dried displayed the highest capacity retention of 90.66% after 50 cycles.

The rhombohedral crystals, which were synthesized at 60°C and air-dried, had a capacity retention of 88.03% after 50 cycles. Moreover, the rhombohedral-structured crystals had a high initial reversible capacity of 150.1 mAh/g with a coulombic efficiency of ≥99.7%.

References

“2021 VTO Annual Merit Review Results Report – Battery R&D.”

Aryal, S., Durham, J. L., Lipson, A. L., et al. (2021). Roles of Mn and Co in Ni-rich layered oxide cathodes synthesized utilizing a Taylor Vortex Reactor. Electrochimica Acta, 39, 138929.

Axmann, P. (2020). “Focus on cobalt-free cathodes.” ZSW Annual Battery Report, 2020, 55.

Choi, M., Kim, H.-S., Kim, J.-S., et al. (2014). Synthesis and electrochemical performance of high-capacity 0.34Li₂MnO₃•0.66LiMn_0.63Ni_0.24Co_0.13O₂ cathode materials using a Couette–Taylor reactor. Materials Research Bulletin, 58, 223-228.

Heo, K., Lee, J., Im, J., et al. (2020). A composite cathode material encapsulated by amorphous garnet-type solid electrolyte and self-assembled La₂(Ni_0.5Li_0.5)O4 nanoparticles for all-solid-state batteries. Journal of Materials Chemistry A, 8, 22893-22906.

Jo, I.-H., Lee, S.-M., Kim, H.-S., Jin, B.-S. (2017). Electrochemical properties of Na_xMnFe(CN)₆•zH₂O synthesized Taylor-Couette reactor as a Na-ion battery cathode material. Journal of Alloys and Compounds, 729, 590-596.

Kim, J.-E. and Kim, W.-S. (2017) Synthesis of Core-Shell Particles of Nickel-Manganese-Cobalt Hydroxides in a Continuous Couette-Taylor Crystallizer. Crystal Growth & Design, 17, 3677-3696.

Schmuch, R., Siozios, V., Winter, M. and Placke, T. (2020). Production of Nickel-Rich Layered Cathode Materials for High-Energy Lithium Ion Batteries via a Couette-Taylor-Flow-Reactor. Material Matters, 15(2), 53-57.

Seenivasa, M., Yang, C.-C., Wu, S.,et al. (2021). Using a CouetteTaylor vortex flow reactor to prepare a uniform and highly stable Li[Ni_0.80Co_0.15Al_0.05]O₂ cathode material. Journal of Alloys and Compounds, 857, 157594.

Thai, D. K., Mayra, Q.-P. and Kim, W.-S. (2015). Agglomeration of Ni-rich hydroxide crystals in Taylor vortex flow. Powder Technology, 274, 5-13.

Yang, S. H., Kim, M. Y., Kim, D. H., et al. (2017). Ionic conductivity of Ga-doped LLZO prepared using Couette-Taylor reactor for all-solid lithium batteries. Journal of Industrial and Engineering Chemistry, 56, 422-427.

Taylor Crystallizer for EV Battery Materials Business Case